fix comments

Signed-off-by: Soragna, Alberto <[email protected]>

Author: alsora

rclcpp/include/rclcpp/executors/events_executor.hpp

@@ -35,7 +35,10 @@ namespace executors
 
 /// Events executor implementation
 /**
- * Add description
+ * This executor is a variation of the standard one that does not uses a waitset.
+ * The executor uses an events queue and a timers manager to execute entities from its
+ * associated nodes and callback groups.
+ * This provides improved performance as it allows to skip all the waitset maintenance operations.
  *
  * To run this executor:
  * rclcpp::executors::EventsExecutor executor;

rclcpp/include/rclcpp/executors/events_executor_notify_waitable.hpp

@@ -75,7 +75,7 @@ class EventsExecutorNotifyWaitable final : public EventWaitable
         false);
 
       if (RCL_RET_OK != ret) {
-        throw std::runtime_error("Couldn't set guard condition callback");
+        throw std::runtime_error("Couldn't set guard condition events callback");
       }
     }
   }